2018-06-11

Sparse stuff:

  • Each processor has a specific set of instructions, called Instruction Set Architecture (ISA)

  • Bit: transistor/switch (on or off)

Assembly language

def. a low-level symbolic code converted by an assembler

ex.

> mov a1, 061h :
  load in register a1 the content of memory location of adress 061h

easier to write but codes are extremely long and hard to read and understand

high-level languages

easier to write and read algorithms

> 1972: Dennis Ritchie at Bell telephone
        Labs develops the C language

> 1979: Bjarne Stroustrup at Bell Labs
        design and implement C++
        (C with classes)

More sparse stuff:

  • compiler: g++

  • command line debugger: gdb

    • not really practical to use

  • Integrated Development Environment (IDE)

  • ##:

    • single line: //
    • multiple lines: /* ... */

multiple file programs and header files

sparse stuff:

types

porto workshop week

operations for variable modification

prefix and postfix

implicit type conversion

ex.

conditional statement

pointer (dereference operator *)

a pointer is a variable that stores the address of another object

  • always initialize a pointer, *, with the value zero

  • pointers can be assigned addresses of other variables via the address-of operator (ampersand) & - the types of the variable and the pointer have to match

exs.

size

  • the size of pointer doesn’t depend on its type

arrays

what Stroustroup says about:

declaration

  • indexes range from 0 to size -1

  • to access an element use the subscript operator [] or through a pointer

boundary checking: C/C++ compiler does no boundary check. Using out of range indexes is not detected by compiler and results in computation errors

array list initialization

sizeof an array

returns the number of bytes allocated for the entire array

multidimensional arrays

for readability, use nested curly brackets

pointer arithmetic (with an ex)

  • number of elements should be constant and could not be changed later

dynamic memory allocation

ex.

program memory

a programs memory is divided into

  • code area: compiled program (executable)

  • globals area: global variables

  • heap: dynamically allocated memory

  • stack: parameters and local variables

strings

c++ 11 doesn’t allow string literals to be assigned to non-const char *

string concatenation

std::string // string class (data type)

string str = "Hello";

index range is 0 to str.length()-1

common string methods

Sys.time()
## [1] "2018-07-08 11:25:38 +03"